The footings for building structures are conventionally prepared by digging trenches in accordance with the architectural and structural design of the building, constructing temporary frameworks for the footing in the trenches, installing temporary rebar supports and installing rebars in the frameworks, pouring concrete paste into the space formed by the frameworks, removing the frameworks before the concrete is fully cured, and refilling the trench with soil after the frameworks are removed and the concrete footing is fully cured. This is a labor intensive and time consuming process.
Recently, prefabricated concrete forms have been developed for stay-in-place with the concrete footing formed, which eliminates the step of removing the temporary frameworks before the concrete is fully cured. However, moving and assembling concrete forms require heavy equipment and extensive physical labor. Further, alignment and support of the heavy concrete forms are difficult, which tends to cause irregularity and deformation of the footing.
Other types of stay-in-place footing frameworks include a prefabricated frame configured for the width of the footing with form board built in or installed at the job site prior to placing in the trenches. Such frameworks are prefabricated for the dimensions of the footing, and are not versatile for different construction needs. Further, installation of rebars in such frameworks may be difficult or inconvenient due to fixed structure of the frameworks.
Moreover, the existing concrete footings, such as concrete spread footing, monolithic concrete footings and concrete stem wall footings, are not resistant to impact forces from earthquakes. In the regions where earthquakes are a major threat to housings and human life, such as in California, Japan, Italy, Chili, and several regions in China, the existing concrete footings as the foundation of housings do not have protections from a direct impact force from earthquakes and are vulnerable to such an impact.
Therefore, there is a strong need for an improved stay-in-place footing form, which are easy to assemble at construction sites and versatile for different footing construction needs, and are able to substantially save time and labor cost of concrete footing constructions. Moreover, there is a strong need for a stay-in-place footing form, as an integral part of a concrete footing, has an ability of absorbing direct impact forces exerted by earthquakes to the concrete footing and hence reducing overall impacts and potential damages to the building structure.